1. Field of the Invention
The present invention generally relates to an image transmitting apparatus for digitally processing an analog video signal, and more particularly to an image transmitting apparatus and an image transmitting system which are capable of efficiently supplying digital image data to a plurality of applications in real time by using a common bus construction.
2. Description of the Related Art
In recent years, along with rapid spread and high speed promotion of a digital network typified by an Internet Protocol (IP), a demand of video contents delivery, and video transmission in a monitoring system or the like is in the progress of increasing. At the same time, for a utilization range of an image as well, the number of application systems for invader detection through image processing using an advanced processor in addition to simple transmission has increased. Apparatuses for realizing these application systems show the spreading from the conventional expensive dedicated apparatus to a miniature desk-stand apparatus and a PC installation type ad-in board depending on the applications. In future, it is estimated that an application for executing data processing such as image recognition, image compression, and image accumulation for a plurality of image inputs is merged therewith, so that a high value added system appears.
FIG. 9 is a block diagram showing a conventional transmitting system. As shown in FIG. 9, a camera 2 outputs data on a captured image in the form of an NTSC signal for example. A video recorder 4 subjects the NTSC signal to analog-to-digital conversion to obtain data on a digital frame image, e.g., an REC601 in accordance with a predetermined standard. When receiving as its input the data on the digital frame image as the REC601, an image compressing/transmitting portion 6 encodes the data on the digital frames image by using a predetermined system, e.g., an MPEG system. The image compressing/transmitting portion 6 forms the encoded frame image data into an IP packet, and transmits the resulting IP packet to a monitoring camera or the like through a network. When receiving as its input the IP packet, the monitoring center decodes the IP packet to display the resulting image on a screen or the like. In such a manner, normally, the digital image data is subjected to one-to-one connection between the output of the video decoder 4 and the data processing portions such as the image compressing/transmitting portion 6 in most of the cases.
However, in the case of the conventional image transmitting system, the digital image data is subjected to one-to-one connection between the video decoder 4 and the data processing portion 6. Hence, in the case where a plurality of image inputs captured with a plurality of cameras, respectively, are generated, a plurality of video decoders and data processing portions must be installed in one apparatus. As a result, a circuit scale increases, and the apparatus has much futility and becomes expensive.
In addition, when single image data is subjected to a plurality of image processing, since the image processing portion cannot be configured with one device, it is necessary that a plurality of image processing portions be provided and the image data be inputted to the plurality of image processing portions, respectively. As a result, a circuit scale increases, and the apparatus has much futility and becomes expensive.
In addition, a plurality of data processing portions may subject a plurality of images captured with a plurality of cameras, respectively, in cooperation with one another. For example, image recognition such as invader detection needs to be performed by a plurality of image recognizing portions which are provided so as to correspond to a plurality of images, respectively. Also, in the case where for example, an invader is detected in an image as a result of the image recognition, it is necessary to provide an image composing portion for performing selection of an invader detection image from a plurality of images, addition of a character message indicating the invader detection, and the like. For this reason, such a problem exists that the apparatus configuration becomes complicated.
Moreover, when data on a plurality of images captured with a plurality of cameras, respectively, is composed into data on one image and the resulting composite data is transmitted, the synchronization must be performed since the data on the video image frames is asynchronously transferred with the normal cameras, respectively. For this reason, it is necessary to synchronize the data on a plurality of image frames which is asynchronously transferred from a time base collector provided in the outside, and to perform the synchronization for the data on output image frames themselves by a genlock camera. As a result, such a problem exists that the apparatus is costly.
Patent document 1 (Japanese Patent Laid-open No. Hei 6-6798) discloses that a plurality of video cameras each including means for sending an analog video signal after time-division multiplexing, and a master control device are connected to each other through one bus line, and the master control device demodulates a time-division multiplex signal to display the resulting image.
Patent document 2 (Japanese Patent Laid-open No. hei 5-2442232) discloses that a multi-media system is provided in which a local bus is provided on a board, and the local bus and a PC are connected to each other through interface means, whereby a memory for display, compressing/expanding means, and the like can be readily extended.
Patent document (International Publication WO97/23093) discloses one image input device for receiving as its input data on an analog moving picture, a video decoder, a moving picture compressing portion for converting digitized data on a moving picture into compressed data on a moving picture a moving picture, input interface portion for transferring the compressed data on the moving picture to a main storage, and the like.
However, in the case of the technique disclosed in Patent document 1, since each of the cameras includes the means for time-division multiplexing the data on the analog image, the cameras are expensive similarly to the genlock camera. Also, as shown in FIG. 4 of Patent document 1, for the time division multiplexing means included in each of the cameras, the number of digital image data to be multiplexed, and the order of accommodation thereof are fixed. From these points, the digital image cannot be displayed on a display device in a state in which the number of digital image data, i.e., the number of cameras is made variable. In addition, one monitor is merely connected to the master control device. Hence, it is impossible to monitor an analog image signal on a plurality of monitors, respectively, e.g., to display a single analog image signal on a plurality of monitors, respectively. Moreover, since Patent document 1 dose not disclose a configuration relating to a plurality of image processing portions, for example, another image processing portion, e.g., an image compressing portion cannot execute image processing based on the recognition results obtained from an image recognizing portion.
Since Patent document 2 does not disclose a technique relating to multiplexing of signals of images captured with a plurality of cameras, respectively, the signals of the images captured with a plurality of cameras, respectively, cannot be simultaneously displayed on a display device. In addition, the single analog video signal cannot be displayed on a plurality of monitors, respectively. Moreover, since Patent document 2 does not disclose a configuration of a plurality of image processing portions, for example, another image processing portion, e.g., an image compressing portion cannot execute image processing based on the recognition results obtained from an image recognizing portion.
Patent document 3 cannot solve any of the abovementioned problems since the technique disclosed therein is the same as that which is firstly explained in the prior art.